From b60974fac8a2f4c85cbb2ca788fc4ec3e81998f9 Mon Sep 17 00:00:00 2001
From: Thomas Devoogdt <thomas.devoogdt@barco.com>
Date: Tue, 17 Aug 2021 11:54:49 +0200
Subject: [PATCH] util: os_same_file_description: fix unknown linux < 3.5
 syscall SYS_kcmp
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https://man7.org/linux/man-pages/man2/kcmp.2.html

The kcmp() system call first appeared in Linux 3.5.

But was probably also not supported by all major platforms
at that time. So fallback to the check that is done for windows.

Signed-off-by: Thomas Devoogdt <thomas.devoogdt@barco.com>
Acked-by: Yonggang Luo <luoyonggang@gmail.com>
Acked-by: Michel Dänzer <mdaenzer@redhat.com>
Upstream: https://gitlab.freedesktop.org/mesa/mesa/-/commit/3ef514982441ce496aa127611edd26b9867f4b95
Signed-off-by: Thomas Devoogdt <thomas@devoogdt.com>
---
 src/util/os_file.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/src/util/os_file.c b/src/util/os_file.c
index 5fb30f2d908..464425a9b87 100644
--- a/src/util/os_file.c
+++ b/src/util/os_file.c
@@ -202,29 +202,23 @@ os_read_file(const char *filename, size_t *size)
 /* copied from <linux/kcmp.h> */
 #define KCMP_FILE 0
 
+#endif
+
 int
 os_same_file_description(int fd1, int fd2)
 {
+#ifdef SYS_kcmp
    pid_t pid = getpid();
+#endif
 
    /* Same file descriptor trivially implies same file description */
    if (fd1 == fd2)
       return 0;
 
+#ifdef SYS_kcmp
    return syscall(SYS_kcmp, pid, pid, KCMP_FILE, fd1, fd2);
-}
-
 #else
-
-int
-os_same_file_description(int fd1, int fd2)
-{
-   /* Same file descriptor trivially implies same file description */
-   if (fd1 == fd2)
-      return 0;
-
    /* Otherwise we can't tell */
    return -1;
-}
-
 #endif
+}
-- 
2.34.1

